We demonstrate the patterning of silica substrates with thymine (Thy-PS) and positively charged N-methylpyridinium (PVMP) polymers using photolithography and the subsequent orthogonal modification of these surfaces using diaminopyridine-functionalized polystyrene (DAP-PS) and carboxylate-derivatized CdSe/ZnS core-shell nanoparticles (COO-NP) through diamidopyridine-thymine three-point hydrogen bonding and pyridinium-carboxylate electrostatic interactions, respectively. This two-component orthogonal surface modification was accomplished in a self-sorting, single-step fashion, providing a versatile tool for the rapid and efficient creation of complex materials.

Utilization of ultrathin grafted nanoparticle (NP) [1][2][3][4] films to impart desired chemical/physical properties onto various solid substrates is a versatile and effective technique for preparing new composite and functional materials. [5][6][7][8] The fabrication of well-defined conductive metallic films is especially important owing to the increasing demand for high-speed and cost-effective electronic devices. [9] The conventional "topdown" lithographic methods, based on multistep resist patterning, etching, washing, and deposition continue to be the industrial fabrication standard; however, integrating these methods with recently developed "bottom-up" assembly strategies offers several preparative, geometric, and operational advantages. [8,[10][11][12][13][14] Metallic and semiconductor NPs are among the most versatile self-assembly building blocks due to their unique optical, magnetic, and electronic properties. [15,16] These properties can be readily manipulated upon assembly by tailoring the interfacial interactions. [17][18][19] The generation of multilayers or even monolayers of NP arrays on modified substrates provides an approach to transparent and/or flexible devices due to the mild fabrication conditions and its application to a variety of substrates. A planar monolayer array of NPs well packed but separated from each other (i.e., no agglomeration) is important for nanoelectronics, [20] as the electronic conduction in such structures varies from metallic to insulating owing to single-electron tunneling, [21][22][23] depending on the interparticle distance and the ligands present on the particles.[13]We recently reported specific and site-selective immobilization of monolayer-protected NPs on polymer-templated surfaces. [24,25] The use of a polymer interface to direct the deposition provides a versatile way to assemble ordered [26] and confined [25,27] 2D NP arrays through lithography and self-assembly. In addition, polymers can be coated on a wide range of substrates and with different topographies under mild conditions. Here, we report a versatile approach to the creation of very regular conductive NP films. In this method, positively charged polyvinyl N-methylpyridine (PVMP) was patterned via photochemical crosslinking, with the resultant cationic surface directing the adsorption of water-soluble citrate-protected Au NPs producing patterned nanostructured conductive films (Fig. 1). These surfaces could be further modified with thiol ligands allowing fine tuning of surface properties such as wettability and biocompatibility. Compared to most other fabrication methods, this photopattering and wet-deposition process is quite straightforward, and operates under ambient "wet" conditions. It also circumvents problems such as crack formation during heat annealing due to volume loss and weak substrate adhesion. Furthermore, this water/alcohol-based fabrication method is free of organic solvents and COMMUNICATION

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[reaction: see text] A model system has been developed to study the redox behaviors of flavin derivatives appended onto random polystyrene copolymers through "click" chemistry strategies. The results demonstrate that flavin units attached onto polymers exhibit site-isolated redox behaviors, yielding new materials with electrochemically tunable associations (K(a)(ox) = 450 M(-)(1), K(a)(red) = 18,200 M(-)(1)) to complementary diamidopyridine (DAP) functionality.